1. Field of the Invention
The present invention relates generally to gyroscopic instruments and is more particularly concerned with two-degree-of-freedom flexure suspended free-rotor gyroscopes.
2. Description of the Prior Art
Flexure suspended free-rotor gyroscopic devices are found in U.S. patents assigned to Sperry Rand Corporation, including:
W. G. Wing--U.S. Pat. No. 2,719,291--"Rate of Turn Gyroscope", issued Sept. 27, 1955, PA1 T. R. Quermann--U.S. Pat. No. 3,529,477--"Gyroscopic Rotor Suspension", issued Sept. 22, 1970, PA1 T. R. Quermann--U.S. Pat. No. 3,557,629--"Pick-Off and Torquing Device", issued Jan. 26, 1971, and PA1 T. R. Quermann--U.S. Pat. No. 3,677,097--"Protective Stops for Flexure Suspended Gyroscopic Rotor", issued July 18, 1972.
These patents disclose concepts illustrating the results of recent efforts in the design of gyroscopic devices to achieve smaller, less expensive, and more reliable gyroscopic instruments for use in precision navigation and stabilization applications, including flight control systems. Some types of such prior art instruments have required either separate pick-offs or rotary transformers and resolvers, these representing complex and expensive expedients unsuited for use wherever compactness of design is a requisite.
On the other hand, the aforementioned U.S. Pat. No. 3,557,629 sought, for example, to overcome the problems of the prior art in providing a more nearly ideal pick-off, torquer, and reference signal generator system for such flexure suspended gyroscopes. In the prior art device of the latter patent, pick-off coils are mounted on the instrument housing, thus eliminating the need for expensive resolver apparatus, and second parts of the pick-off are located on the gyroscope rotor drive shaft. The torquing function is made generally integral with the pick-off function, thereby making the configuration relatively more compact than devices requiring fully separated pick-off and torquer devices. However, a large number of coils is required in the pick-off coil assembly, as well as a complex magnetic circuit difficult specifically to design in compact form and in general to machine and to assemble. It is also found to be difficult to eliminate all coupling between torquer and pick-off circuits.